A series of studies are in progress to determine whether or not human platelets have receptor sites for bacterial endotoxin, for staphylococcal protein A, and for aggregated immunoglobulins. These studies will employ radio-iodinated platelets and labeled endotoxin, SPA, and IgG, to attempt to demonstrate physical association of the challenge material with the platelet membrane. If this can be accomplished, it will be possible to investigate the biochemical nature of the receptor site. A series of studies on the immunopathology of schistosomiasis under Dr. Daniel G. Colley continues in this laboratory, with the most recent effort being directed at the isolation and chemical characterization of a lymphokine-like material derived from the supernatant fluid of lymphocytes obtained from infected mice and stimulated with soluble egg antigen. As a third major interest, the laboratory intends to investigate several aspects of platelet physiology in the uremic state, specifically prostaglandin metabolism, and uptake and release of labeled serotonin.